TopJimi has some profiles of a 63 Bassman (the one with the 6g6 circuit that Brian uses) that sound nice. But the real key to his tone (besides his chops) is the preamp in the Space Echo. It's like a HiFi preamp and makes every note stand out.
I use a DynoBrain in front of my Kemper with this profile and that's it! Now just many years of practice....